IHE portable data profile fixes interoperability snags

The shift from film-based images and hard-copy reports to soft-copy reading and digital archiving has sparked challenges when it comes to sharing and distributing data. Referring physicians and patients now typically expect to receive medical data and images on portable media such as compact discs and DVDs. But not all of these portable devices are reliably interoperable with PACS and enterprise IT systems.

As technology has advanced, the use of portable media devices has proliferated, and each type of device is accompanied by its own format. With such a plethora of options, the interoperability desired by healthcare providers has been difficult to achieve.

To promote consistency, DICOM has defined allowable media formats such as CD, DVD, and module file format and developed restrictions to improve data exchange. In addition to defining the physical media, DICOM also created application profiles, which define types of compatible images and their formats. The standards group established a directory file to index the information on the media.

Despite the great strides made by DICOM, lack of interoperability among portable media has continued to be a challenge. A new profile has been developed by the Integrating the Healthcare Enterprise initiative in response to this need.

The IHE analyzed the reasons behind incompatibility and three years ago created the portable data for imaging (PDI) integration profile. The main issues identified by the IHE include:

• limitations of physical media;
• limitations of DICOM application profiles;
• physical definition of the directory setup;
• inclusion of non-DICOM data on the portable media;
• proper identification of portable media; and security.

The profile, which is beginning to gain wider acceptance, addresses each of these issues. Concerning physical limitations, for example, although additional types of portable media such as DVD may be added to the profile in the future, at this time only CDs have been sufficiently defined at the interoperability level.

DICOM LIMITATIONS

Limitations of DICOM applications, such as compression, also present challenges for interoperability. As a result, the new profile supports only uncompressed image sets. It also clarifies DICOM requirements that have frequently been overlooked or misunderstood, such as strict adherence to the ISO 9660 Level 1. It specifies other requirements to ensure interoperability between devices using different operating systems.

The goal of the profile is to support a range of needs for portable media, from radiologists using PACS or dedicated display workstations to referring physicians using simple viewers or browsers on standard PCs. The new profile allows users to access data with simple browsers. These browsers are indicated by specific entry points and permit Web content such as JPEG images, PDF documents, and HTML pages to be included on the CD. The profile also defines a fixed directory structure (see table) that aids the applications that are reading the CD.

If medical data are reliably exchanged, the primary goal of the IHE will have been met. If Web content is present, however, the profile requires proper inclusion of encoded data. The IHE profile also specifies creation of a text file that identifies the institution where the data were created, as well as information on how the data are organized. This information may be helpful in managing the data if problems occur.

SECURITY MEASURES

Last but not least, the guidelines also note that the portable media should be visibly identifiable to clinicians as adhering to the PDI profile. Related security measures include running antivirus software when the CD is created and ensuring that auto-run applications are not enabled.

The new IHE PDI profile is a reliable way of distributing imaging data and has been well accepted by the industry. The IHE profile will support additional types of portable media when reliable interoperability choices can be made.

The organization continues its goal of reliable exchange of medical data despite ongoing interoperability challenges. For more information on the IHE profile, investigate links to the PDI available from the Radiology Technical Framework located at www.ihe.net.

Ms. Levy is the standards team leader for Cedara Software, a Merge Healthcare company, in Milwaukee.